To measure the protective efficacy of 3 spaced doses of vaccine against experimental challenge with wild type S. flexneri 2a 2457T [ Time Frame: approximately October 2010 ] [ Designated as safety issue: No ]

Secondary Outcome Measures:

To assess the fecal shedding of wild type S. flexneri 2a in vaccinees and controls following challenge [ Time Frame: approximately October 2010 ] [ Designated as safety issue: Yes ]

To elucidate the systemic and mucosal immune responses in vaccinees and control subjects following challenge with wild type S. flexneri 2a [ Time Frame: approximately October 2009, January 2010, and August - October 2010 ] [ Designated as safety issue: No ]

To examine which immune responses correlate with protection against experimental challenge [ Time Frame: approximately October 2010 ] [ Designated as safety issue: No ]

The study comprises a Phase 2 vaccination study and a Phase 2b challenge study. The primary objectives of the Phase 2 vaccination study are: 1. To evaluate, in healthy volunteers, the safety and clinical acceptability of three spaced doses (one month apart) of an investigational, live, oral, attenuated vaccine called CVD 1208S, with particular attention to the occurence of diarrhea, dysentery, and fever, and 2. To characterize immune responses following ingestion of this vaccine. The primary objective of the Phase 2b challenge study is to measure the protective efficacy of 3 spaced doses of vaccine after ingestion of an oral challenge strain called Shigella flexneri 2a strain 2457T.

Shigella is a leading cause of disease and death among children younger than 5 years living in developing countries. The difficulty controlling this infection has led experts to believe that prevention with the use of a vaccine is a promising strategy. At the CVD, we have pursued an approach of developing an oral, attenuated Shigella vaccine that prevents infection with the Shigella types of greatest clinical and epidemiologic importance. One of the strains to be included in the vaccine is called Shigella flexneri 2a. Investigators at the CVD have created a vaccine from Shigella flexneri 2a, designated CVD 1208S, using molecular biology techniques. To date, nearly 40 subjects have received varying doses of this vaccine with good clinical tolerance and modest immunogenicity. Previously a single dose of vaccine was used. In the current study, we will administer doses of vaccine on days 0, 28, and 56 to attempt to maximize immunogenicity. Approximately one month after the 3rd dose, a group of ~15-20 vaccinated volunteers along with a similar number of unvaccinated control subjects will be admitted to the CVD Research Isolation Ward at SNBL and challenged with wild type Shigella flexneri 2a. By comparing the attack rate of illness in vaccinated vs. unvaccinated subjects, we will determine the vaccine's ability to confer protective immunity.

Eligibility

Ages Eligible for Study:

18 Years to 45 Years (Adult)

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

Yes

Criteria

Inclusion Criteria:

Age 18 to 45 years, inclusive

Good general health as determined by a screening evaluation within 45 days before inoculation

Expressed interest and availability to fulfill study requirements

Informed, written consent

Agrees to indefinite storage of unused clinical specimens at the CVD for use in future research, which may require separate IRB approval

Agrees not to participate in another investigational vaccine or drug trial during the 6-month study

Has no childbearing potential, i.e., either surgically sterilized or 1 year postmenopausal, or agrees to abstain from becoming pregnant from the day of screening (at least 14 days before vaccination) through Day 42 of the trial by using one of the following methods of birth control:

An acute or chronic medical condition that, in the opinion of the investigator, would render vaccination unsafe or would interfere with the evaluation of responses. This includes, but is not limited to:

Repeated (two or more) seizures occurring after 5 years of age, and not related to a concussion

Any of the following in the past 10 years: Crohn's disease, ulcerative colitis, irritable bowel disease, celiac disease, stomach or intestinal ulcers, or 2 or more episodes of arthritis (joint pain and swelling);

Blood in stool on more than 2 occasions (other than small amounts from straining) in past 12 months

Recurrent diarrhea (more than 5 episodes in past 6 months, each lasting 3 days or more)

Immunosuppression as a result of an underlying illness or treatment within the preceding 36 months,

long term use of steroids, or high-dose inhaled steroids (greater than 800 micrograms/day of beclomethasone dipropionate or equivalent) within the preceding 6 months (Nasal and topical steroids are allowed)

History of the following types of abdominal surgery:

Any major gastrointestinal surgery (e.g., intestinal resection or splenectomy)

A laparotomy for any reason (e.g., hysterectomy, Caesarian section, appendectomy, or herniorrhaphy) within the last 3 years

Laparoscopic abdominal surgery within the past year

A large abdominal scar of unclear origin

Medical, occupational, or family problems as a result of alcohol or illicit drug use during the past 12 months

Known allergy or intolerance to ciprofloxacin, trimethoprim/sulfamethoxazole (or other sulfa antibiotic) or ampicillin (for women)

History of shigellosis or Shigella vaccination (except as a participant in Part A of this study) or challenge or a laboratory worker with known exposure to Shigella

During the past 3 years, developed diarrhea during travel to a developing country, or within 1 week of returning home

Anticipates any of the following during 30 days after discharge from the Isolation Ward:

Shares a household with a child less than 3 years of age, a pregnant woman, or a woman who plans to become pregnant during this time period

Household or sexual contact with someone who has weakened immunity (such as someone with HIV infection, someone receiving treatment for cancer, or an elderly person greater than 70 years)

Occupation as a food-handler, childcare (for children less than 3 years), or health care worker with direct patient contact

Poor peripheral access for placement of an intravenous line

A clinically significant abnormality on physical examination, including, but not limited to:

Positive serum pregnancy test during medical screening or within 24 hours of challenge, or current breast feeding (women)

A psychological condition, including a personality, anxiety, or affective disorder, and schizophrenia, which in the opinion of a clinical psychologist compromises the ability of the volunteer to tolerate an inpatient trial

Receipt of any of the following (does not include the CVD 1208S vaccine):

Any vaccine or investigational drug within 30 days of challenge

A live, attenuated vaccine within the 30 days of the challenge

A subunit or killed vaccine within the 14 days of the challenge

A blood product, including immunoglobulin, in the 90 days before the challenge

Receipt of antibiotics within 7 days of inoculation (or within 21 days if the antibiotic was azithromycin)

Loose stools (grade 3-5) or any other acute illness such as fever greater than or equal to 100.4 degrees F during the 48 hour acclimation on the inpatient ward that continues until time of challenge

Other condition that in the opinion of the investigator would jeopardize the safety or rights of a study participant or render the subject unable to comply with the protocol.

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00866242

Locations

United States, Maryland

Shin Nippon Biomedical Laboratories (SNBL) Inpatient Facility

Baltimore, Maryland, United States, 21201

University of Maryland, Baltimore Center for Vaccine Development

Baltimore, Maryland, United States, 21201

Sponsors and Collaborators

University of Maryland

PATH

Investigators

Principal Investigator:

Karen L Kotloff, M.D.

University of Maryland, Baltimore Center for Vaccine Development

More Information

Responsible Party:

Karen Kotloff, MD, Professor of Pediatrics and Medicine, University of Maryland